[derefr]

That's like saying that spaceships are extremely efficient, because "all they have to do is accelerate at the beginning and decelerate at the end." It's not the trip that gets you; it's the delta-V (or in this case, delta-p).

Also, cargo shipping voluntarily uses fuel ("bunker fuel" — the dregs of the petroleum distillation process) that's absolutely awful for the environment per watt generated compared to any other fuel (including any other petroleum distillate.) They do this because it's the cheapest [liquid] fuel to buy per watt generated, and because they "can" — cargo-ship engines are designed to deal with the low quality of bunker fuel, and ships at sea under most of the common charters [e.g. Bermuda] aren't subject to any ecological regulations restricting them from burning it.

Bunker fuel shouldn't be marketable for sale as a fuel at all. We (= OPEC, in this case) could still sell it to chemical companies, but the rest, we should just be sticking back in the ground. This would reduce global greenhouse gas emissions by such an extent it's not even funny.

This would naturally make shipping more expensive, since their next-cheapest fuel would be slightly more expensive. (Probably not for long, though; some capital investment into ship engine design, using modern engine technologies like Cylinder Deactivation, could probably claw most of this cheapness back.)

[snovv_crash]

Yes, bunker fuel is terrible. But this doesn't change the fact that most of the carbon emissions would still be there for domestic production, because ships are extraordinarily efficient per tonne-mile of goods hauled.

[derefr]

The carbon emissions would still be there, but they might not be nearly as toxic/hazardous. (See my reply to a sibling comment.)

On the other hand, they'd be happening over land, where people live; instead of over water, "merely" killing marine life, so that might be a wash in policy-makers' minds.

To be clear, though, I'm not arguing against using cargo ships for domestic logistic as a concept; just the current implementation. Cargo ships that didn't use bunker fuel would be an unalloyed ecological win compared to both domestic ground logistics, and the current implementation of domestic marine logistics.

[throwaway894345]

But that doesn’t change the fact that no amount of efficiency can make domestic shipping + oceanic shipping cheaper than domestic shipping alone.

[tomarr]

>Bunker fuel shouldn't be marketable for sale as a fuel at all. We (= OPEC, in this case) could still sell it to chemical companies, but the rest, we should just be sticking back in the ground. This would reduce global greenhouse gas emissions by such an extent it's not even funny.

Bunker fuel is responsible for ~3% of CO2e emissions? OK it may have a greater impact on air quality, but in terms of carbon it is not exactly a stand-out item.

[derefr]

Carbon is a heuristic, not a target. The air isn't bad because of carbon; carbon oxides are just the most common of the GHGs we put in the air.

Bunker fuel contains a lot more light-molecular-weight things that aren't hydrocarbons (e.g. nitrogenous molecules), and so when they burn, you end up with toxic GHGs being produced, rather than just bad for climate change GHGs. (And, as you mention, the fact that we're burning it mostly at the beginning and end of the trip, means we're burning it near ports, and therefore making the air at port cities — and nearby estuaries — toxic.)

But even then, the concern with bunker fuel in particular isn't really the GHGs (i.e. the low-molecular-weight products of combustion that stay airborne), but all the high-molecular-weight stuff that's mixed in there, that doesn't stay airborne, but is temporarily put into the air during combustion.

Bunker fuel is "dirty fuel", using a similar sense of "dirty" to a "dirty bomb" — not that it's radioactive, but that it "salts the earth" where it goes off. Except that a bunker-fuel "bomb" goes off over water, and all the resulting heavy-molecular-weight vapors that come off the combustion then fall into said water, contaminating the oceans+estuaries with these chemicals. Bunker fuel salts the sea.

[Schiendelman]

As a single line item, that’s vast.